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Release 4.10 drivers/watchdog/sc520_wdt.c

Directory: drivers/watchdog
/*
 *      AMD Elan SC520 processor Watchdog Timer driver
 *
 *      Based on acquirewdt.c by Alan Cox,
 *           and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net>
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 *
 *      The authors do NOT admit liability nor provide warranty for
 *      any of this software. This material is provided "AS-IS" in
 *      the hope that it may be useful for others.
 *
 *      (c) Copyright 2001    Scott Jennings <linuxdrivers@oro.net>
 *           9/27 - 2001      [Initial release]
 *
 *      Additional fixes Alan Cox
 *      -       Fixed formatting
 *      -       Removed debug printks
 *      -       Fixed SMP built kernel deadlock
 *      -       Switched to private locks not lock_kernel
 *      -       Used ioremap/writew/readw
 *      -       Added NOWAYOUT support
 *      4/12 - 2002 Changes by Rob Radez <rob@osinvestor.com>
 *      -       Change comments
 *      -       Eliminate fop_llseek
 *      -       Change CONFIG_WATCHDOG_NOWAYOUT semantics
 *      -       Add KERN_* tags to printks
 *      -       fix possible wdt_is_open race
 *      -       Report proper capabilities in watchdog_info
 *      -       Add WDIOC_{GETSTATUS, GETBOOTSTATUS, SETTIMEOUT,
 *              GETTIMEOUT, SETOPTIONS} ioctls
 *      09/8 - 2003 Changes by Wim Van Sebroeck <wim@iguana.be>
 *      -       cleanup of trailing spaces
 *      -       added extra printk's for startup problems
 *      -       use module_param
 *      -       made timeout (the emulated heartbeat) a module_param
 *      -       made the keepalive ping an internal subroutine
 *      3/27 - 2004 Changes by Sean Young <sean@mess.org>
 *      -       set MMCR_BASE to 0xfffef000
 *      -       CBAR does not need to be read
 *      -       removed debugging printks
 *
 *  This WDT driver is different from most other Linux WDT
 *  drivers in that the driver will ping the watchdog by itself,
 *  because this particular WDT has a very short timeout (1.6
 *  seconds) and it would be insane to count on any userspace
 *  daemon always getting scheduled within that time frame.
 *
 *  This driver uses memory mapped IO, and spinlock.
 */


#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/timer.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/fs.h>
#include <linux/ioport.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/io.h>
#include <linux/uaccess.h>


/*
 * The AMD Elan SC520 timeout value is 492us times a power of 2 (0-7)
 *
 *   0: 492us    2: 1.01s    4: 4.03s   6: 16.22s
 *   1: 503ms    3: 2.01s    5: 8.05s   7: 32.21s
 *
 * We will program the SC520 watchdog for a timeout of 2.01s.
 * If we reset the watchdog every ~250ms we should be safe.
 */


#define WDT_INTERVAL (HZ/4+1)

/*
 * We must not require too good response from the userspace daemon.
 * Here we require the userspace daemon to send us a heartbeat
 * char to /dev/watchdog every 30 seconds.
 */


#define WATCHDOG_TIMEOUT 30		
/* 30 sec default timeout */
/* in seconds, will be multiplied by HZ to get seconds to wait for a ping */

static int timeout = WATCHDOG_TIMEOUT;
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout,
	"Watchdog timeout in seconds. (1 <= timeout <= 3600, default="
				__MODULE_STRING(WATCHDOG_TIMEOUT) ")");


static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
		"Watchdog cannot be stopped once started (default="
				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

/*
 * AMD Elan SC520 - Watchdog Timer Registers
 */

#define MMCR_BASE	0xfffef000	
/* The default base address */

#define OFFS_WDTMRCTL	0xCB0	
/* Watchdog Timer Control Register */

/* WDT Control Register bit definitions */

#define WDT_EXP_SEL_01	0x0001	
/* [01] Time-out = 496 us (with 33 Mhz clk). */

#define WDT_EXP_SEL_02	0x0002	
/* [02] Time-out = 508 ms (with 33 Mhz clk). */

#define WDT_EXP_SEL_03	0x0004	
/* [03] Time-out = 1.02 s (with 33 Mhz clk). */

#define WDT_EXP_SEL_04	0x0008	
/* [04] Time-out = 2.03 s (with 33 Mhz clk). */

#define WDT_EXP_SEL_05	0x0010	
/* [05] Time-out = 4.07 s (with 33 Mhz clk). */

#define WDT_EXP_SEL_06	0x0020	
/* [06] Time-out = 8.13 s (with 33 Mhz clk). */

#define WDT_EXP_SEL_07	0x0040	
/* [07] Time-out = 16.27s (with 33 Mhz clk). */

#define WDT_EXP_SEL_08	0x0080	
/* [08] Time-out = 32.54s (with 33 Mhz clk). */

#define WDT_IRQ_FLG	0x1000	
/* [12] Interrupt Request Flag */

#define WDT_WRST_ENB	0x4000	
/* [14] Watchdog Timer Reset Enable */

#define WDT_ENB		0x8000	
/* [15] Watchdog Timer Enable */


static __u16 __iomem *wdtmrctl;

static void wdt_timer_ping(unsigned long);
static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);

static unsigned long next_heartbeat;

static unsigned long wdt_is_open;

static char wdt_expect_close;
static DEFINE_SPINLOCK(wdt_spinlock);

/*
 *      Whack the dog
 */


static void wdt_timer_ping(unsigned long data) { /* If we got a heartbeat pulse within the WDT_US_INTERVAL * we agree to ping the WDT */ if (time_before(jiffies, next_heartbeat)) { /* Ping the WDT */ spin_lock(&wdt_spinlock); writew(0xAAAA, wdtmrctl); writew(0x5555, wdtmrctl); spin_unlock(&wdt_spinlock); /* Re-set the timer interval */ mod_timer(&timer, jiffies + WDT_INTERVAL); } else pr_warn("Heartbeat lost! Will not ping the watchdog\n"); }

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dave jonesdave jones5887.88%125.00%
jiri slabyjiri slaby46.06%125.00%
joe perchesjoe perches23.03%125.00%
wim van sebroeckwim van sebroeck23.03%125.00%
Total66100.00%4100.00%

/* * Utility routines */
static void wdt_config(int writeval) { unsigned long flags; /* buy some time (ping) */ spin_lock_irqsave(&wdt_spinlock, flags); readw(wdtmrctl); /* ensure write synchronization */ writew(0xAAAA, wdtmrctl); writew(0x5555, wdtmrctl); /* unlock WDT = make WDT configuration register writable one time */ writew(0x3333, wdtmrctl); writew(0xCCCC, wdtmrctl); /* write WDT configuration register */ writew(writeval, wdtmrctl); spin_unlock_irqrestore(&wdt_spinlock, flags); }

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dave jonesdave jones7298.63%150.00%
wim van sebroeckwim van sebroeck11.37%150.00%
Total73100.00%2100.00%


static int wdt_startup(void) { next_heartbeat = jiffies + (timeout * HZ); /* Start the timer */ mod_timer(&timer, jiffies + WDT_INTERVAL); /* Start the watchdog */ wdt_config(WDT_ENB | WDT_WRST_ENB | WDT_EXP_SEL_04); pr_info("Watchdog timer is now enabled\n"); return 0; }

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dave jonesdave jones2961.70%120.00%
wim van sebroeckwim van sebroeck1123.40%240.00%
jiri slabyjiri slaby48.51%120.00%
joe perchesjoe perches36.38%120.00%
Total47100.00%5100.00%


static int wdt_turnoff(void) { /* Stop the timer */ del_timer(&timer); /* Stop the watchdog */ wdt_config(0); pr_info("Watchdog timer is now disabled...\n"); return 0; }

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dave jonesdave jones2172.41%125.00%
wim van sebroeckwim van sebroeck620.69%250.00%
joe perchesjoe perches26.90%125.00%
Total29100.00%4100.00%


static int wdt_keepalive(void) { /* user land ping */ next_heartbeat = jiffies + (timeout * HZ); return 0; }

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static int wdt_set_heartbeat(int t) { if ((t < 1) || (t > 3600)) /* arbitrary upper limit */ return -EINVAL; timeout = t; return 0; }

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wim van sebroeckwim van sebroeck35100.00%2100.00%
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/* * /dev/watchdog handling */
static ssize_t fop_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { /* See if we got the magic character 'V' and reload the timer */ if (count) { if (!nowayout) { size_t ofs; /* note: just in case someone wrote the magic character * five months ago... */ wdt_expect_close = 0; /* now scan */ for (ofs = 0; ofs != count; ofs++) { char c; if (get_user(c, buf + ofs)) return -EFAULT; if (c == 'V') wdt_expect_close = 42; } } /* Well, anyhow someone wrote to us, we should return that favour */ wdt_keepalive(); } return count; }

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dave jonesdave jones8284.54%120.00%
wim van sebroeckwim van sebroeck1313.40%240.00%
alan coxalan cox11.03%120.00%
al viroal viro11.03%120.00%
Total97100.00%5100.00%


static int fop_open(struct inode *inode, struct file *file) { /* Just in case we're already talking to someone... */ if (test_and_set_bit(0, &wdt_is_open)) return -EBUSY; if (nowayout) __module_get(THIS_MODULE); /* Good, fire up the show */ wdt_startup(); return nonseekable_open(inode, file); }

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dave jonesdave jones3363.46%120.00%
wim van sebroeckwim van sebroeck1019.23%240.00%
alan coxalan cox917.31%240.00%
Total52100.00%5100.00%


static int fop_close(struct inode *inode, struct file *file) { if (wdt_expect_close == 42) wdt_turnoff(); else { pr_crit("Unexpected close, not stopping watchdog!\n"); wdt_keepalive(); } clear_bit(0, &wdt_is_open); wdt_expect_close = 0; return 0; }

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dave jonesdave jones3976.47%125.00%
wim van sebroeckwim van sebroeck1019.61%250.00%
joe perchesjoe perches23.92%125.00%
Total51100.00%4100.00%


static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { void __user *argp = (void __user *)arg; int __user *p = argp; static const struct watchdog_info ident = { .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE, .firmware_version = 1, .identity = "SC520", }; switch (cmd) { case WDIOC_GETSUPPORT: return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; case WDIOC_GETSTATUS: case WDIOC_GETBOOTSTATUS: return put_user(0, p); case WDIOC_SETOPTIONS: { int new_options, retval = -EINVAL; if (get_user(new_options, p)) return -EFAULT; if (new_options & WDIOS_DISABLECARD) { wdt_turnoff(); retval = 0; } if (new_options & WDIOS_ENABLECARD) { wdt_startup(); retval = 0; } return retval; } case WDIOC_KEEPALIVE: wdt_keepalive(); return 0; case WDIOC_SETTIMEOUT: { int new_timeout; if (get_user(new_timeout, p)) return -EFAULT; if (wdt_set_heartbeat(new_timeout)) return -EINVAL; wdt_keepalive(); /* Fall through */ } case WDIOC_GETTIMEOUT: return put_user(timeout, p); default: return -ENOTTY; } }

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al viroal viro2410.57%110.00%
alan coxalan cox20.88%220.00%
Total227100.00%10100.00%

static const struct file_operations wdt_fops = { .owner = THIS_MODULE, .llseek = no_llseek, .write = fop_write, .open = fop_open, .release = fop_close, .unlocked_ioctl = fop_ioctl, }; static struct miscdevice wdt_miscdev = { .minor = WATCHDOG_MINOR, .name = "watchdog", .fops = &wdt_fops, }; /* * Notifier for system down */
static int wdt_notify_sys(struct notifier_block *this, unsigned long code, void *unused) { if (code == SYS_DOWN || code == SYS_HALT) wdt_turnoff(); return NOTIFY_DONE; }

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dave jonesdave jones35100.00%1100.00%
Total35100.00%1100.00%

/* * The WDT needs to learn about soft shutdowns in order to * turn the timebomb registers off. */ static struct notifier_block wdt_notifier = { .notifier_call = wdt_notify_sys, };
static void __exit sc520_wdt_unload(void) { if (!nowayout) wdt_turnoff(); /* Deregister */ misc_deregister(&wdt_miscdev); unregister_reboot_notifier(&wdt_notifier); iounmap(wdtmrctl); }

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dave jonesdave jones2571.43%150.00%
wim van sebroeckwim van sebroeck1028.57%150.00%
Total35100.00%2100.00%


static int __init sc520_wdt_init(void) { int rc = -EBUSY; /* Check that the timeout value is within it's range ; if not reset to the default */ if (wdt_set_heartbeat(timeout)) { wdt_set_heartbeat(WATCHDOG_TIMEOUT); pr_info("timeout value must be 1 <= timeout <= 3600, using %d\n", WATCHDOG_TIMEOUT); } wdtmrctl = ioremap(MMCR_BASE + OFFS_WDTMRCTL, 2); if (!wdtmrctl) { pr_err("Unable to remap memory\n"); rc = -ENOMEM; goto err_out_region2; } rc = register_reboot_notifier(&wdt_notifier); if (rc) { pr_err("cannot register reboot notifier (err=%d)\n", rc); goto err_out_ioremap; } rc = misc_register(&wdt_miscdev); if (rc) { pr_err("cannot register miscdev on minor=%d (err=%d)\n", WATCHDOG_MINOR, rc); goto err_out_notifier; } pr_info("WDT driver for SC520 initialised. timeout=%d sec (nowayout=%d)\n", timeout, nowayout); return 0; err_out_notifier: unregister_reboot_notifier(&wdt_notifier); err_out_ioremap: iounmap(wdtmrctl); err_out_region2: return rc; }

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wim van sebroeckwim van sebroeck6543.33%450.00%
dave jonesdave jones4228.00%112.50%
randy dunlaprandy dunlap2516.67%112.50%
joe perchesjoe perches1610.67%112.50%
alan coxalan cox21.33%112.50%
Total150100.00%8100.00%

module_init(sc520_wdt_init); module_exit(sc520_wdt_unload); MODULE_AUTHOR("Scott and Bill Jennings"); MODULE_DESCRIPTION( "Driver for watchdog timer in AMD \"Elan\" SC520 uProcessor"); MODULE_LICENSE("GPL");

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dave jonesdave jones67854.20%516.67%
wim van sebroeckwim van sebroeck43734.93%930.00%
joe perchesjoe perches322.56%13.33%
al viroal viro262.08%26.67%
randy dunlaprandy dunlap252.00%13.33%
alan coxalan cox191.52%413.33%
jiri slabyjiri slaby181.44%13.33%
andrew mortonandrew morton60.48%26.67%
alexey dobriyanalexey dobriyan40.32%13.33%
tim schmielautim schmielau30.24%13.33%
arjan van de venarjan van de ven10.08%13.33%
sean youngsean young10.08%13.33%
andrey paninandrey panin10.08%13.33%
Total1251100.00%30100.00%
Directory: drivers/watchdog
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